Explosive devices and explosively activated devices have been developed and are used to perform many functions today. For example, airbags in automobiles and other motor vehicles are explosively activated devices and explosively activated devices are also used extensively in mining, excavation, rocket ignition and various other firing systems. In each explosively activated device, the explosion must be initiated and this is typically done by ignition or detonation.
Explosive devices typically fall into two or more basic groups. The first group is electro-thermally initiated devices which respond to relatively low electrical energies. The second group is electro-shock initiated devices which include exploding wire and foil designs requiring very high energy levels. While electro-shock initiated devices have the advantages of fast and repeatable function times and also exhibit a very high resistance to inadvertent initiation, they normally require high initiation energies and power levels which lead to larger and more expensive electrical firing systems.
Electro-thermally initiated devices therefore enjoy the advantage of operating at lower initiation energies and can be smaller and easier to produce. The ignition systems and devices used to activate these explosively activated devices should desirably be easy to ignite, compact, efficient, easy to manufacture, reliable and should include safeguards against undesirably igniting.
Although various ignition systems for electro-thermally initiated devices exist, it would be desirable to produce smaller ignition devices with smaller features and which can be heated or otherwise activated much faster and using less energy than conventional devices. It would also be desirable to produce such devices to include safeguards against undesirable ignition. It would further be desirable to manufacture such miniaturized ignition devices using well known and well understood conventional methods that allow for simultaneously manufacturing multiple devices in a small area.